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Linus Torvalds and Linux

Abstract

On 25 August 1991, a 21-year-old computer science student in Helsinki posted to a Usenet newsgroup that he was building a free operating system for 386 computers, “just a hobby, won’t be big and professional like gnu.” Linus Torvalds put the kernel under the GNU General Public License in 1992, accepted patches from anyone by email and kept the final say over what went in. Version 1.0 came out in March 1994. Combined with the tools of the GNU Project and packaged by distributions, Linux became the operating system of most web servers, of the public cloud, of every Android phone and, since November 2017, of every computer on the TOP500 list of supercomputers. In April 2005, after the company behind the version-control system the kernel used withdrew its free licence, Torvalds wrote Git in a few weeks; it is now the version-control system of almost all software development. On the desktop, where he most wanted Linux to win, it stayed a niche.

Linus Torvalds
Linus Torvalds at LinuxCon Europe, 2014. Image: Krd, Von Sprat, CC BY-SA 4.0, via Wikimedia Commons.

Helsinki

Linus Benedict Torvalds was born in Helsinki on 28 December 1969 to the journalists Anna and Nils Torvalds. The family belongs to Finland’s Swedish-speaking minority. In 1981, at eleven, he began programming a Commodore VIC-20 that his grandfather, a statistician at the University of Helsinki, had bought. He entered the University of Helsinki in 1988 to study computer science, interrupted his studies in 1989 for eleven months of officer training in the Finnish Navy’s Nyland Brigade, and left it as a second lieutenant.

On 5 January 1991 he bought a PC clone with an Intel 386 processor. The operating system he wanted on it was a Unix like the one on the university’s computers, and the closest available was MINIX, the teaching system that Andrew Tanenbaum had written to accompany his textbook. MINIX came with its source code, but it cost money, its licence did not allow it to be freely redistributed, and Tanenbaum kept it deliberately simple for teaching. Torvalds used MINIX, and its source code and Tanenbaum’s book taught him how an operating system kernel worked.

A Hobby Kernel

Torvalds first wrote a terminal emulator that ran directly on the hardware, so he could dial in to the university’s Unix machines. To download files he needed to read and write the disk, and to do that he needed a file system driver. The emulator was turning into an operating system kernel.

On 25 August 1991 he posted to comp.os.minix:

“I’m doing a (free) operating system (just a hobby, won’t be big and professional like gnu) for 386(486) AT clones. This has been brewing since april, and is starting to get ready.”

Version 0.01, about 10,000 lines of code, went up on the FTP server of the Finnish university network FUNET on 17 September 1991. Torvalds wanted to call it “Freax”; the server’s administrator, Ari Lemmke, named the directory “linux” instead, and the name stayed (see Linux Was Freax). The first licence forbade selling it. With version 0.12, effective 1 February 1992, Torvalds switched to Richard Stallman’s GNU General Public License (GPL), version 2, which requires anyone who distributes modified versions to publish their changes under the same terms. He later said that “making Linux GPLed was definitely the best thing I ever did.” The licence kept companies from taking the kernel private, and it put Linux on the same terms as the GNU tools (the GCC compiler, the bash shell, the C library) that together with the kernel made a complete system.

Myth: Linus Torvalds wrote all of Linux.

Torvalds wrote, and still maintains, the kernel, the core that manages hardware, memory and processes. A kernel alone is not a usable operating system. The shell, compiler (GCC), C library (glibc), core utilities and most of the user-space software that makes a Linux system work came from Richard Stallman’s GNU Project, begun in 1983, which is why many insist on the name GNU/Linux. The kernel itself is now the work of thousands of contributors and hundreds of companies; Torvalds writes a small fraction of each release. His decisive contributions were starting the kernel and running its development. See Myths and Misconceptions.

Linux had no office, no team and no company. Patches arrived by email from programmers around the world; Torvalds read them, accepted some, rejected others and released new versions, sometimes several a week. Eric Raymond analysed the method in “The Cathedral and the Bazaar” (1997), contrasting the planned, closed “cathedral” of traditional software projects with the open “bazaar” of Linux, where, as he put it, “given enough eyeballs, all bugs are shallow.”

Torvalds vs. Tanenbaum

In January 1992 Tanenbaum posted “LINUX is obsolete” to comp.os.minix. Linux was a monolithic kernel, with all of its code running in one address space, which he considered a design of the 1970s; MINIX was a microkernel, with drivers and services running as separate processes. He also argued that tying Linux to the 386 made it hard to port. Torvalds replied the same evening. He agreed that microkernels were nicer in theory, but Linux was available now, MINIX did the microkernel job badly (its file system could not handle several requests at once), and Linux was portable where it mattered, at the level of its programming interface. He added that “your job is being a professor and researcher: That’s one hell of a good excuse for some of the brain-damages of minix.”

The debate is told in detail in Andrew Tanenbaum and MINIX. Linux won the market. The portability argument was settled in Linux’s favour too: it was ported from the 386 to dozens of processor architectures. Research systems such as L4 later showed that microkernels could be fast, and MINIX 3 ended up inside Intel’s chipsets, but by then Linux’s installed base was out of reach.

From 1.0 to Infrastructure

Linux 1.0 was released on 14 March 1994. Version 2.0 (1996) added support for multiprocessor machines. The same year Linux got its mascot, Tux, a penguin drawn by Larry Ewing with the then-new free image editor GIMP; Torvalds had been nibbled by a fairy penguin during a visit to a zoo in Canberra around 1993 and wanted a penguin. In 1995 William Della Croce had registered the trademark “Linux” in the United States and in 1996 began demanding royalties of 10 percent from companies selling Linux products. Five Linux companies and individuals challenged the registration, and in August 1997 Della Croce assigned the trademark to Torvalds in a settlement.

In February 1997 Torvalds moved to California to work for Transmeta, a start-up developing low-power processors that translated x86 instructions in software, and maintained Linux on the side. In June 2003 he joined the Open Source Development Labs, an industry consortium, to work on the kernel full-time, and in June 2004 he moved with his family to Oregon. On 22 January 2007 OSDL and the Free Standards Group announced their merger into the Linux Foundation, which employs him. He became a U.S. citizen in 2010.

Kernel versions followed a steady rhythm: 2.2 in 1999, 2.4 in 2001, 2.6 in 2003, then 3.0 in 2011, 4.0 in 2015, 5.0 in 2019 and 6.0 in 2022, with Torvalds increasing the first number whenever the second got too long to his taste. In December 2022, with version 6.1, Rust became the second language accepted for kernel development after C. The size of the code grew from those 10,000 lines to tens of millions (see 10,000 to 27 Million); how the companies paying the developers came to do so is told in The Open Source Business Model, and how the kernel reached users in The Linux Distributions.

Git

For its first decade the kernel used no version-control system at all: contributors emailed patches and Torvalds applied them to his own tree. From 2002 the project used BitKeeper, a commercial distributed version-control system whose developer, Larry McVoy, let kernel developers use it free of charge. Many developers objected to depending on proprietary software. In April 2005 McVoy accused Andrew Tridgell, the author of Samba, of reverse-engineering BitKeeper’s protocols to write an open-source client, and withdrew the free licence.

Torvalds had strong views on what he needed: a distributed system in which every developer had the full history, fast enough to apply hundreds of patches in seconds, and safe against corruption. He found none of the existing free systems (CVS, Subversion, Monotone, Arch) acceptable and began writing his own on 3 April 2005. He announced it on 6 April; on 7 April Git was managing its own source code, on 18 April it performed its first merge of several branches, and Linux 2.6.12 (16 June 2005) was the first kernel release managed with it. Git stores every file, directory and commit under a cryptographic hash of its contents, which makes any corruption detectable and identical content stored only once. Torvalds explained the name, British slang for an unpleasant person, by saying: “I’m an egotistical bastard, and I name all my projects after myself. First ‘Linux’, now ‘git’.”

On 26 July 2005 he handed maintenance to Junio Hamano, who released version 1.0 on 21 December 2005 and still maintains it. GitHub, founded in 2008, built a social network for programmers around Git repositories, and within a decade Git had displaced almost every other version-control system. The wider history is told in The Rise of Version Control.

The Licence and the Maintainers

When the Free Software Foundation drafted version 3 of the GPL in 2006, Torvalds refused to move the kernel to it. His objection was to its provisions against hardware that only runs signed software, the kind used for digital rights management: in his view a software licence should not tell hardware makers how to design their devices, and since the kernel’s licence names version 2 only and its copyright is held by thousands of contributors, a change would have needed the agreement of all of them. Linux remains under version 2.

The kernel is developed through a hierarchy of maintainers. Maintainers of subsystems (networking, file systems, individual drivers) collect patches from their areas and send them to Torvalds during a two-week “merge window” at the start of each release cycle, after which only fixes are accepted; a new version appears roughly every nine to ten weeks.

Torvalds’ tone on the mailing list was for decades blunt and often abusive. On 16 September 2018 the kernel replaced its “Code of Conflict” with a Code of Conduct, and Torvalds apologised for personal attacks he called “unprofessional and uncalled for” and took time off; he returned after version 4.19 was released on 22 October. In October 2024 several Russian developers working for sanctioned companies were removed from the list of maintainers; Torvalds answered critics with “Did you think I’d be supporting Russian aggression?”

He shared the Millennium Technology Prize of the Technology Academy Finland in 2012 and received the IEEE Computer Pioneer Award in 2014.

Dead End: Linux on the Desktop

Linux runs on servers, phones, embedded systems and supercomputers. On the desktop it reached about 4 percent of the worldwide market in mid-2025 by StatCounter’s count of web page views, and a little over 5 percent in the United States, after three decades of predictions that “this year” would be “the year of Linux on the desktop.”

The Desktop Problem

Windows came preinstalled on almost every PC sold, while Linux had to be installed by the user. Commercial software for professional design, accounting and games was largely missing, and hardware makers wrote drivers for Windows first, if at all. The distributions also split the desktop between several environments and packaging systems, so an application vendor had no single target. The attempts to sell Linux to ordinary PC buyers, from Corel Linux to Lindows, are told in The Linux Distributions. Torvalds himself has said he wants Linux to win the desktop and remains frustrated that it has not.

Valve’s Steam Deck (2022) runs a Linux system, and its Proton compatibility layer runs Windows games on it (see Valve and Steam). The movement Linux grew out of is covered in The Open Source Revolution.

📚 Sources